1. Field of the Invention
The present invention relates to solid state line scanning devices and more particularly to a line scanner having a diode oscillator which is located between two oppositely extending dielectric waveguides with spaced metal stripes on opposite sides.
The present device may find application in radar.
2. Description of the Prior Art
Microwave technology requires various circuit components for use in applications in the fields of radar and communications. Typically such circuit components include filter elements, oscillator sources, and/or scanning antennas for use in beam steering applications. While various circuits for millimeter-wave applications have been described in the literature, there is an ongoing effort to provide simple and low cost devices which are able to perform several circuit functions in one integrated structure.
An earlier dielectric waveguide scanning device is described in U.S. Pat. No. 4,203,117, issued to two of the present inventors, which discloses a dual beam line scanner. The device provides steered fan shaped beams from opposite faces at substantially equal angles of a single semiconductor waveguide. The waveguide has a plurality of equally spaced parallel perturbations, such as metal stripes, attached to one of the two radiation sides or faces, the stripes being transverse to the principal direction of radiation. The angle of scan is selectively controlled by variably biasing a PIN diode that is integrally formed on an adjoining side of the waveguide. However, variation of the PIN bias causes variation in radiated power and there is no simple, effective way of controlling the angle of scan of the beam with respect to the waveguide while maintaining a uniform power output. Furthermore, since the PIN diode is formed by deposition of contiguous layers of semiconductor material directly upon the side of a semiconductor waveguide, should the diode burn out or be damaged, the entire assembly must be discarded and replaced.
Another related device is described in U.S. Pat. No. 4,382,261, issued to two of the present inventors and another, which also discloses a dual beam line scanner having two integral PIN diodes on opposite faces with a dielectric layer under each diode.
A further related device of two of the present inventors is described in copending application Ser. No. 679,970, filed Dec. 10, 1984, and now U.S. Pat. No. 4,590,441, which utilizes a single longitudinal dielectric waveguide with perturbations on its upper surface and a housing with a resonant cavity and diode oscillator. Frequency is controlled by varying bias on the oscillator or on a second varactor diode in a second cavity. The device also contains a reflector located opposite the waveguide on the other side of the oscillator, which serves to reflect energy escaping from the cavity back into the cavity and thence into the single waveguide.
Also of interest is the following publication: IEEE Transactions on MMicrowave Theory and Techniques, Vol. MTT-32, No. 2, February 1984, R. E. Horn et al, "Integrated Tunable Cavity Gunn Oscillator for 60-GHz Operation in Image Line Waveguide," pp 171-176, which discusses a mechanically tunable Gunn oscillator coupled to an image line waveguide.
However none of these references shows or suggests a device having the particular structure and advantages of the present invention.